Hybrid vehicles combine traditional fuel-powered engines with electric motors to improve fuel economy. To achieve better fuel economy, a hybrid vehicle includes a traction battery that stores energy for use by the electric motors. During normal operation, the state of charge of the battery may fluctuate. The battery may be charged while driving by controlling the engine and a generator to provide power to the battery. Additionally, a plug-in hybrid may recharge the battery by plugging in to an external power supply.
A hybrid vehicle may also be adapted to provide power to loads external to the vehicle. The vehicle may have a plug-out mode where an external load can be connected to the vehicle. In the plug-out mode, the vehicle provides power to the external load. One possible application may be to provide electrical power to a house as a backup generator. For example, the vehicle power bus may be connected to an external inverter that converts DC voltage to an AC voltage compatible with household devices. The traction battery may provide the power or the engine may be operated to drive a generator to provide the external power.